Integrated cast motorcycle chassis and motor housing

ABSTRACT

This invention comprises a frame for an electric motorcycle. Electric motorcycles have vastly different component requirements compared to internal combustion engine motorcycles, and, therefore, require a radical redesign of the frame in order to maximize the efficiency of the system.

FIELD

The invention relates to vehicles, and, more particularly to electricmotorcycle frames.

BACKGROUND

Recent advances in electric vehicle technology have resulted vehiclesthat have comparable performance characteristics compared to internalcombustion engine vehicles. Unfortunately, one key component, thebattery, remains stubbornly expensive, resulting in costly electriccars. One cannot possibly justify the price of a new electric carcompared to a similarly equipment gasoline or diesel model. If, instead,one develops the lightest possible vehicle, the electric equation justmight make sense.

The lightest practical vehicle is either a motocross bike, a streetlegal equivalent, the enduro, or it's fully street focused version, thesupermoto. Such bikes often weigh a little over 100 kg. By minimizingweight, the battery requirements are minimized, and, consequently, theprice as well.

Several companies have seen the light and jumped into the fray.Unfortunately, their efforts have come up short. Many save the expenseof designing a new chassis from scratch, and, instead, shoehorn anelectric motor and battery pack in a frame that was originally designedfor and internal combustion engine. The results have been mediocre,underpowered bikes with limited range and questionable handling.

The published US patent application 2011/0036657 A1 by Bland et al.(subsequently referred to as Bland) assigned to Brammo Inc. discloses astraight electric motorcycle chassis that comprises two sides thatenclose the headstock and allow attachment of batteries from above andbelow. Bland places the motor at the axis of the drive sprocket, with notransmission, subsequently requiring a big, heavy electric motor togenerate enough torque. The motor is also fully stressed, resulting inhigh maintenance costs related to motor repair or replacement. Inaddition, the batteries are insufficient for a reasonable top speed andrange.

Zero Motorcycles, from Scotts Valley, Calif., manufactures an electricmotorcycle frame using a combination of tubular and hydroformed aluminumpieces that are welded together. The myriad disadvantages of weldedaluminum frames are discussed in the description, below. Like theteachings of Bland, the Zero batteries are insufficient for a reasonabletop speed and range.

KTM of Austria and Quantya of Switzerland both employ welded bent steeltube perimeter frames, which can be heavy.

All of the electric motorcycle manufacturers discussed above use aircooled electric motors. Compared to liquid cooled electric motors, aircooled electric motors have lower peak power outputs and vastly lowercontinuous power outputs.

Given growing consumer demand for high performance, low cost electricvehicles, there is a need for a new electric motorcycle developed arounda new type of chassis.

SUMMARY

The current invention relates to a vehicle frame, or chassis, and itsmanufacture. In one embodiment the frame comprises two cast aluminumstructures that can be bolted together. The frame structures can each becast in one piece and finish machined with one fixturing. The framecasting can include an integral motor housing that may be fully stressedand act as a torsion tube.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 shows a motorcycle.

FIG. 2 shows motorcycle parts that attach to a motorcycle frame.

FIG. 3 shows motorcycle parts that attach to a motorcycle frame.

FIG. 4 shows a rear part of a motorcycle frame.

FIG. 5 shows a rear part of a motorcycle frame.

FIG. 6 shows a rear part of a motorcycle frame.

FIG. 7 shows a rear part of a motorcycle frame.

FIG. 8 shows a front part of a motorcycle frame.

FIG. 9 shows a front part of a motorcycle frame.

DESCRIPTION

FIG. 1 shows a motorcycle 100. The motorcycle 100 shown is an off roador motocross bike. Motorcycles 100 comprise motocross bikes, road bikes,three wheeled bikes, and four wheeled bikes. Any three or four wheeledvehicle where the rider straddles the seat 114 of the vehicle isconsidered a motorcycle. Scooters are also considered motorcycles. Themotorcycle 100 shown in FIG. 1 comprises an electric motorcycle, and,therefore has an electric motor and a battery box 112.

FIG. 2 shows motorcycle parts that attach to a motorcycle frame 144.Shown are a shroud 102, also known as a fairing, a seat 114, a rearsubframe 116, a rear shock 140, a swing arm 138, a rear suspensionlinkage 130, a skid plate 142, a battery box 112, a motor cover 122, asprocket 136, and a fork 134. Also shown are the frame structure 200 andthe second frame structure 300.

FIG. 3 shows motorcycle parts that attach to a motorcycle frame 144.Shown are a radiator 104, a water pump 128, a footpeg 126, a rear mastercylinder 124, and a gear cover 120. Also shown are the frame structure200 and the second frame structure 300.

A frame 144 for a motorcycle can be made as a single piece or severalpieces that are attached together. The example frame 144 shown in FIGS.2-3 is a two piece frame 144 comprising the frame structure 200, alsoknown as a rear bulkhead, and the second frame structure 300, also knownas a front bulkhead. The two piece frame 144 design allows the framestructure 200 and the second frame structure 300 to each be cast as asingle piece, finish machined in one fixture, and attached together.

Using only one fixture per structure reduces time required for machiningand increases accuracy of the machined surfaces. Milling machines largeenough for a single structure can be cost prohibitive. Utilizing twostructures, rather than a single structure, reduces the size of millingmachine required to complete the operation, reducing capital costs. Inaddition, separating the structure into two pieces can allow machineaccess to additional areas of the casting, allowing more features to beintegrated and reducing the complexity of fixturing and machining.Casting a single frame unit may also be quite complicated and morecostly that two smaller frame castings.

A typical 3-axis milling machine setup involves clamping the workpiecein a vise where only one face is exposed for cutting at a time. A 4-axismill setup clamps the workpiece in a rotary fixture. This allows themachine to work on virtually all faces of the workpiece that areperpendicular to the axis of rotation. Thus, by using a 4-axis millingmachine, such as a horizontal milling machine with a rotary axis for theworkpiece fixture, one can finish machine all of the features, orinterface areas, within the tolerance specification for the framestructure 200 and the second frame structure 300 listed below and seenin FIGS. 4-9 with one fixturing per piece, each saving considerable timeand expense.

In one embodiment, the frame 144 may be manufactured by casting both theframe structure 200 and the second frame structure 300 each as a singlecasting from 206 aluminum alloy. The frame structure 200 and the secondframe structure 300 castings are then separately mounted in respectivefixtures and features are finish machined in at least one working plane.206 aluminum has some corrosion issues, so conversion coating, a processincluding an acid dip and passivation, followed by priming and paintingwould resolve those issues. Other suitable casting aluminum alloysinclude 201, 204, 356, and 357. In another embodiment, a one piece framemay be manufactured by casting the frame 144 as a single casting withmost or all of the features and mounting points included in FIGS. 2-8and then finish machined. In yet another embodiment, the frame structure200 may be cast and finish machined as described above, while the secondframe structure 300 may be fabricated in another manner, such as milledfrom billet aluminum or created by welding two or more parts together.Welding allows one to build a trellis frame structure out of steel,titanium, or aluminum or to build a twin spar aluminum frame structurecommonly used for motorcycles. Alternatively, the second frame structure300 may be built out of a composite material such as carbon fiber.

The embodiment of the frame 144 shown in FIG. 3 with the frame structure200 and the second frame structure 300 comprises a weldless design.Welding frame components can take a considerable amount to time toaccurately fixture and weld together. Welding adds expense due toinconsistencies in weld quality that require a safety margin or morerobust and heavy structure to compensate for these inconsistencies.Welding can also result in stress build up and distortion in a structurerequiring secondary heat treatment and straightening.

FIG. 4 shows a rear part of a motorcycle frame 144. The frame structure200 includes frame mounts 202, a gear cover mount 206, rear subframemounts 208, linkage mounts 210, rear master cylinder mounts 212, batterybolt holes 214, skid plate mounts 216, footpeg mounts 218, a rear brakelever mount 220, shroud mounts 222, a bottom coolant port 238, an oilsump 232, a right side 240, a motor housing 244, an output shaft housing246, a vent hole 248, and a shock mount bolt hole 254.

FIG. 5 shows a rear part of a motorcycle frame 144. The frame structure200 includes shock mounts 204, a motor cover mount 224, a pass throughhole 226, swing arm mounts 228, a top coolant port 230, a left side 242,a motor housing 244, an output shaft housing 246, a vent hole 248, and astructural rib 250.

The left and right sides 242, 240 shown in FIGS. 4, 5 are a type of sidestructure that connects the motor housing 244, which may act as atorsion tube, to mounting points for other components or to other framefeatures. The sides 242, 240 are shown as part of a single casting, butmay also be a welded trellis structure or a composite structure. It isalso possible to use only one side structure in the middle of the frameto connect the motor housing 244 to other features and mounting points.

FIG. 6 shows a rear part of a motorcycle frame 144. The frame structure200 includes an oil sump 232, a drain plug port 234, a bottom coolantport 238, a motor housing 244, an output shaft housing 246, structuralribs 250, and battery box mounts 252.

FIG. 7 shows a rear part of a motorcycle frame 144. The frame structure200 includes a pass through hole 226, a motor housing 244, and an outputshaft housing 246.

The left side 242 and right side 240 of the frame structure 200 flankthe motor housing 244 and output shaft housing 246. The housings 244,246 may extend beyond the external wall of the sides 240, 242, or thehousings 244, 246 may be contained by the sides 240, 242. Alternately,one or more sides may be connected to the middle of the housings 244,246. The housings 244, 246 may be fully stressed and may act as torsiontubes to add rigidity to the frame structure 200. Cylinders are the beststructure to use for a torsion tube due to its polar moment of inertia,but other shapes can be used if appropriate. The motor housing 244 bedesigned to receive a motor, preferably a liquid cooled electric motor.The housing 244 may have a top coolant port 230 and a bottom coolantport 238 to allow the circulation of a coolant between the motor housing244 and the motor.

When the motor housing 244 is used as an outer water jacket forcontaining coolant between itself and the motor, the motor can becontained by an inner water jacket. In this case, the motor and theinner water jacket are not required to be stressed members, while themotor housing 244 may be fully stressed.

A motor cover 122 may be attached to a motor cover mount 224 on theframe structure 200 in order to seal the motor from the elements.Likewise, a gear cover 120 may be attached to a gear cover mount 206 inorder to seal the motor and/or gear reduction assembly from theelements. A shroud 102 or fairing may be attached to shroud mounts 216,304. A seat 114 may be attached to seat plate mounts 324 via a seat clipand to the rear subframe 116. The rear subframe 116 may be attached torear subframe mounts 208. A rear shock 140 may be attached to shockmounts 204. A swing arm 138 may be attached to swing arm mounts 228.Rear suspension linkages 130 may be attached to linkage mounts 210.

A skid plate 142 may be attached to skid plate mounts 216 in order toprotect the a battery box 112. A battery box 112 may be attached tobattery box mounts 252 and secured with bolts passing through thebattery bolt holes 214. Any feature that generally aids in theattachment of the battery box 112 to the frame 144 may be generallyreferred to as a battery box mount. The battery box 112 may be a semistressed member when attached to the frame structure 200, thereby addingrigidity to the frame 144 when attached while being removable withoutcompromising the structural integrity of the frame 144 or having therest of the motorcycle 100 lay in pieces when the battery box 112 isremoved, as would be the case if the battery box 112 where fullystressed. A sprocket 136 may drive a chain to drive the rear wheel andmay also be attached to an output shaft that is housed in the outputshaft housing 246.

One or more pass through holes 226, or openings, may be used to allowpassage of hoses and wires. Adding a pass through hole 226 on the motorhousing 244, as seen in FIG. 7, allows the wires that power the motor tobe routed internally in the frame 144, a more attractive and safersolution than routing power wires externally. An o-ring or equivalentseal between the motor housing 244 and the motor can prevent coolantfrom entering the chamber where the power wires connect to the motor. Arubber gasket or equivalent is preferably set in the pass through hole226 to form a seal between the motor housing 244 and the wires and toprovide strain relief.

One or more vent holes 248, 308 allow air to flow through the radiator104 and to exit the frame 144. One or more structural ribs 250 may beadded to the frame structure 200 to increase rigidity.

An oil sump 232 may be placed in the output shaft housing 246 to providelubrication for a gear reduction. The oil sump 232 can be drained via adrain plug port 234. An oil level sight and oil fill port may beintegrated into the gear cover 120. A water pump 128 may be attached toa water pump mount 236, the water pump 128 circulating a coolant to themotor and optionally to the motor control unit and the battery.

FIG. 8 shows a front part of a motorcycle frame 144. The second framestructure 300 includes frame mounts 302, shroud mounts 304, a headstockstructure 306, vent holes 308, a right side 310, a structural rib 314,battery box mounts 316, skid plate mounts 318, steering stop mounts 320,radiator mounts 322, seat plate mounts 324, and a mounting plane 326.The headstock structure 306 is designed for receiving a fork 134. Theheadstock structure 306 may be a tube as shown in FIG. 8 or any otherstructure that holds upper and lower bearings that receive a fork 134. Abox construction type headstock structure 306 may be used to allowgreater airflow through the front of the motorcycle 100.

FIG. 9 shows a front part of a motorcycle frame 144. The second framestructure 300 includes frame mounts 302, shroud mounts 304, a headstockstructure 306, a left side 312, a structural rib 314, battery box mounts316, skid plate mounts 318, steering stop mounts 320, radiator mounts322, seat plate mounts 324, and an access hole 328. The headstockstructure 306 may receive a fork 134. The left and right sides 312, 310are attached to the headstock structure 306. A structural rib 314attaches to the left and right sides 312, 310, aids in structuralrigidity, and helps keep the left and right sides 312, 310 in placeduring the casting and finish machining process. The seat plate mounts324 may receive a plate or clip that receives the seat 114. The accesshole 328 can allow access to the radiator fill cap. The battery boxmounts 316 may receive a battery box 112. The skid plate mounts 318 mayreceive a skid plate 142. The steering stop mounts 320 may receivesteering stops. The radiator mounts 322 may receive a radiator 104.

In addition to having the ability to cool the motor with a coolant, theframe 144 itself can act as a heat sink. Aluminum is a very good heatconductor, and the shape of the frame structure 200 allows excess headto travel from the motor housing 244 to the left and right sides 242,240 of the frame structure 200 where the heat may be dissipated via airconvection, conduction to attached parts, or radiation.

The left and right sides 242, 240 of the frame structure 200 as shown inFIGS. 4-7 comprise a perimeter frame construction to allow for theconnection of parts including the rear swingarm 138, rear suspensionlinkage 130, rear shock 140, rear subframe 116, and fork 134. Alternateconstructions include a trellis frame construction and a composite frameconstruction.

Reference Numerals

-   100 motorcycle-   102 shroud-   104 radiator-   106 steering dampener-   108 steering stop-   110 skid plate-   112 battery box-   114 seat-   116 rear subframe-   118 shock-   120 gear cover-   122 motor cover-   124 rear master cylinder-   126 foot peg-   128 water pump-   130 rear suspension linkage-   134 fork-   136 sprocket-   138 swing arm-   140 shock-   142 skid plate-   144 frame-   200 frame structure-   202 frame mount-   204 shock mount-   206 gear cover mount-   208 rear subframe mount-   210 linkage mount-   212 rear master cylinder mount-   214 battery bolt hole-   216 skid plate mount-   218 footpeg mount-   220 rear brake lever mount-   222 shroud mount-   224 motor cover mount-   226 pass through hole-   228 swing arm mount-   230 top coolant port-   232 oil sump-   234 drain plug port-   236 water pump mount-   238 bottom coolant port-   240 right side-   242 left side-   244 motor housing-   246 output shaft housing-   248 vent hole-   250 structural rib-   252 battery box mount-   254 shock mount bolt hole-   300 second frame structure-   302 frame mount-   304 shroud mount-   306 headstock tube-   308 vent hole-   310 right side-   312 left side-   314 structural rib-   316 battery box mount-   318 skid plate mount-   320 steering stop mount-   322 radiator mount-   324 seat plate mount-   326 mounting plane-   328 access hole

What is claimed is:
 1. A frame for an electric vehicle, the framecomprising: a fully stressed torsion tube configured to house anelectric motor; a first part of the frame including a headstockstructure configured to connect a front suspension to the first part ofthe frame; and a second part of the frame including a shock mountconfigured to connect a rear suspension to the second part of the frame.2. The frame of claim 1, wherein the second part of the frame furthercomprises: a rear subframe mount configured to connect a rear subframeto the second part of the frame.
 3. An electric motorcycle frame, theframe comprising: a first frame structure, the first frame structurecomprising: a first torsion tube configured to house an electric motor;and at least one mount for attaching additional components to the firstframe structure, wherein the first torsion tube is fully stressed in thefirst frame structure.
 4. The frame of claim 3, where the first framestructure further comprises: at least one side structure, where the atleast one side structure connects the at least one mount to the firsttorsion tube.
 5. The frame of claim 3, where the first frame structurefurther comprises: at least one structural rib.
 6. The frame of claim 3,where the first torsion tube includes at least one port for a coolantflow.
 7. The frame of claim 3, where the first frame structure is castas a single casting.
 8. The frame of claim 3, where the first torsiontube is configured to function as an outside water jacket for containinga coolant that circulates between the first torsion tube and the motor.9. The frame of claim 3, where the first frame structure comprises aheat sink for the electric motor.
 10. The frame of claim 3, where thefirst torsion tube includes an opening for passing through electricwires to power the electric motor.
 11. The frame of claim 3, where thefirst frame structure further comprises: a second torsion tube.
 12. Theframe of claim 11, where the second torsion tube comprises an outputshaft housing, and where the second torsion tube is fully stressed. 13.The frame of claim 3, where the at least one mount comprises: at leastone swing arm pivot mount.
 14. The frame of claim 13, where the firstframe structure further comprises: an oil sump, where the oil sumpreinforces the at least one swing arm pivot mount.
 15. The frame ofclaim 3, where the at least one mount comprises: at least one mount fora battery box, where the battery box is a semi stressed member whenattached to the first frame structure.
 16. The frame of claim 3, wherethe first frame structure further comprises: a headstock structureconfigured to connect a motorcycle fork to the first frame structure.17. The frame of claim 3, where the first frame structure comprisesaluminum.
 18. The frame of claim 3, where the first frame structurecomprises magnesium.
 19. The frame of claim 3, further comprising: asecond frame structure configured to attach to the first framestructure, and where the second frame structure includes a headstockstructure configured to connect a motorcycle fork to the second framestructure.
 20. The frame of claim 19, where the second frame structureis fabricated.
 21. The frame of claim 19, where the second framestructure is cast as a single casting.
 22. The frame of claim 21, wherethe second frame structure includes at least one structural rib.
 23. Analuminum frame for an electric motorcycle, the frame comprising: a firstframe structure, the first frame structure comprising: a first side; asecond side; a cylindrical motor housing; a cylindrical output shafthousing; at least one structural rib; a first swing arm pivot; a secondswing arm pivot; and an oil sump, where the cylindrical output shafthousing is flanked by the first side and second side, where thecylindrical output shaft housing is fully stressed, where thecylindrical motor housing is flanked by the first and second sides,where the cylindrical motor housing is a fully stressed torsion tube,where the cylindrical motor housing includes a first port and a secondport for a coolant flow, where the cylindrical motor housing isconfigured to function as an outside water jacket for containing acoolant that circulates between the cylindrical motor housing and anelectric motor, where the cylindrical motor housing and the framecomprise a heat sink for the electric motor, where the cylindrical motorhousing has an opening for passing through electric wires to power theelectric motor, where the electric motor, without the motor housing, isnot stressed, where the oil sump reinforces the first swing arm pivotand the second swing arm pivot, where the at least on structural rib isflanked by the first side and the second side, where a battery box is asemi stressed member when attached to the first frame structure, andwhere the first frame structure is cast as a single casting; and asecond frame structure, the second frame structure comprising: a firstside; a second side; at least one structural rib; and a headstockstructure, where the at least on structural rib is flanked by the firstside and the second side, where the headstock structure is connected tothe first side and the second side, where the second frame structureattaches to the first frame structure, where the headstock structure isconfigured to connect a motorcycle fork to the second frame structure,where the second frame structure is cast as a single casting, where thefirst frame structure and the second frame structure are weldless, andwhere the first frame structure and the second frame structure aremachined to have features comprising: at least one shroud mount; atleast one radiator mount; at least one steering dampener mount; at leastone steering stop mount; at least one skid plate mount; at least onebattery box mount; at least one rear subframe mount; at least one shockmount; at least one gear cover mount; at least one motor cover mount; atleast one rear master cylinder mount; at least one foot peg mount; atleast one rear suspension linkage mount; at least one water pump mount;at least one brake mount; and a drain plug port for the oil sump.